EP0725594B1 - Fingerprinting recording method - Google Patents

Abstract

A fingerprinting method and a device therefor are disclosed. The method essentially comprises the steps of applying a developer powder with phosphorescent properties onto the fingerprint (1) on any substrate (2), adequately illuminating the fingerprint, forming a darkened region at least over the portion of the substrate (2) which bears the fingerprint (1), taking one or more pictures of the darkened fingerprint (1), and displaying, filing, processing, editing, transmitting and/or scanning the resulting pictures.

Description

The present invention relates to identification techniques and highlighting actionable evidence or evidence, and legally valid, in particular by taking into account traces characteristics left by individuals, and relates to a process fingerprint reader, as well as a device for implementation and use of a specific developer for this purpose.

Currently, fingerprints are generally, in view of their exploitation, photographed after revelation by deposit a suitable powder, the color, nature and composition of which depend on the characteristics (color, texture, reflection index, etc.) of the material support bearing the imprint, requiring the contribution constant of a plurality of different powders on the premises of noted.

In addition, the aforementioned powder technique is faulty in many cases, especially when the supports are polychromatic, printed, rough or shiny, resulting in non-usable readings.

In addition, this technique often requires, in order to attempt obtain exploitable results, the use of a impression using adhesive film or chemical treatment prior to the support (check for example). These interventions additions necessarily deteriorate or distort fingerprints who are subject to it, increasing reading difficulties and analysis of these, or even making these operations impossible to achieve.

It is also known a method of taking fingerprints based on the excitation of a powder of a dye (substance fluorescent) by a beam of strong laser energy and the shooting of the resulting fluorescent imprint (cf. US-A-4,794,260).

However, this method, although in some cases more efficient than the previous one, due to the bulky equipment necessary, difficult to implement in situ, and can give rise to the observation of artifacts.

The object of the present invention is in particular to alleviate all of the aforementioned drawbacks and allow obtaining results of a quality clearly superior to those obtained with the state of the techniques exposed above, even for supports not usable by the aforementioned techniques.

To this end, the present invention relates to a method of fingerprint record on any material medium, having the characteristics described in claim 1.

la figure 1 est une vue schématique du dispositif conforme à l'invention;

la figure 2A représente l'image d'une empreinte peu visible sur un chèque sous éclairage naturel;

la figure 2B représente l'image de l'empreinte de la figure 2A relevée au moyen du procédé conforme à l'invention;

les figures 2C et 2D représentent respectivement l'image de l'empreinte de la figure 2B après deux traitements numériques distincts complémentaires;

la figure 3A représente l'image d'une empreinte peu visible sur un billet de banque sous éclairage naturel;

la figure 3B représente l'image de l'empreinte de la figure 3A relevée au moyen du procédé conforme à l'invention;

les figures 3C et 3D représentent respectivement l'image de l'empreinte de la figure 3B après deux traitements numériques distincts complémentaires;

la figure 4A représente l'image d'une empreinte peu visible sur un emballage plastique d'un quotidien délivré par routage, sous éclairage naturel;

la figure 4B représente l'image de l'empreinte de la figure 4A relevée au moyen du procédé conforme à l'invention après augmentation du contraste dans les zones sous-exposées;

les figures 4C et 4D représentent respectivement l'image de l'empreinte de la figure 4B après deux traitements numériques distincts complémentaires;

les figures 5A à 5D représentent les images d'une empreinte à cheval sur l'étiquette et le corps en matière plastique transparent d'une bouteille remplie de liquide, respectivement sous éclairage naturel (5A), telle que relevée par l'intermédiaire du procédé conforme à l'invention (5B) et telle qu'elle se présente après deux traitements numériques distincts complémentaires de l'image de la figure 5B (5C et 5D);

les figures 6A à 6D représentent les images d'une empreinte sur un manche en bois, respectivement, sous éclairage naturel (6A), telle que relevée par l'intermédiaire du procédé conforme à l'invention (6B) et telle qu'elle se présente après deux traitements numériques distincts et complémentaires de l'image de la figure 6B (6C et 6D);

les figures 7A à 7D représentent les images d'une empreinte sur une publicité polychrome sur support papier, respectivement, sous éclairage naturel (7A), telle que relevée au moyen du procédé conforme à l'invention (7B) et telle qu'elle se présente après deux traitements numériques distincts et complémentaires de l'image de la figure 7B (7C et 7D);

les figures 8A à 8D représentent les images d'une empreinte présente sur un manche en bois, identique à celui de la figure 6A, respectivement, sous éclairage naturel (8A), telle que relevée par l'intermédiaire de la technique de fluorescence laser de l'art antérieur (8B) et telle qu'elle se présente (8C et 8D) après deux traitements numériques distincts similaires à ceux ayant aboutis aux figures 6C et 6D, et,

les figures 9A à 9D représentent les images d'une empreinte présente sur une publicité polychrome similaire à celle de la figure 7A, respectivement, sous éclairage naturel (9A), telle que relevée par l'intermédiaire de la technique de fluorescence laser de l'art antérieur (9B) et telle qu'elle se présente (9C et 9D) après deux traitements numériques distincts similaires à ceux ayant aboutis aux figures 7C et 7D.

The invention will be better understood thanks to the description below, which relates to a preferred embodiment, given by way of nonlimiting example, and explained with reference to the appended schematic drawings, in which:

Figure 1 is a schematic view of the device according to the invention;

FIG. 2A represents the image of an imprint that is barely visible on a check under natural light;

FIG. 2B represents the image of the imprint of FIG. 2A taken by means of the method according to the invention;

FIGS. 2C and 2D respectively represent the image of the imprint of FIG. 2B after two complementary separate digital processing;

FIG. 3A represents the image of an imprint that is barely visible on a bank note under natural light;

FIG. 3B represents the image of the imprint of FIG. 3A taken by means of the method according to the invention;

FIGS. 3C and 3D respectively represent the image of the imprint of FIG. 3B after two separate complementary digital treatments;

FIG. 4A represents the image of an imprint little visible on a plastic packaging of a daily newspaper delivered by routing, under natural lighting;

FIG. 4B represents the image of the imprint of FIG. 4A taken by means of the method according to the invention after increasing the contrast in the underexposed areas;

FIGS. 4C and 4D respectively represent the image of the imprint of FIG. 4B after two separate complementary digital processing operations;

FIGS. 5A to 5D represent the images of an imprint straddling the label and the transparent plastic body of a bottle filled with liquid, respectively under natural light (5A), as detected by the process according to the invention (5B) and as it appears after two separate digital processing operations complementary to the image of FIG. 5B (5C and 5D);

FIGS. 6A to 6D represent the images of an imprint on a wooden handle, respectively, under natural lighting (6A), as noted by the intermediary of the method according to the invention (6B) and as it stands present after two distinct and complementary digital processing of the image of FIG. 6B (6C and 6D);

FIGS. 7A to 7D represent the images of an imprint on a polychrome advertisement on paper support, respectively, under natural lighting (7A), as noted by means of the method according to the invention (7B) and as it stands. present after two distinct and complementary digital processing of the image of FIG. 7B (7C and 7D);

FIGS. 8A to 8D represent the images of an imprint present on a wooden handle, identical to that of FIG. 6A, respectively, under natural light (8A), as noted by means of the laser fluorescence technique of the prior art (8B) and as it stands (8C and 8D) after two separate digital processing operations similar to those having resulted in FIGS. 6C and 6D, and,

FIGS. 9A to 9D represent the images of an imprint present on a polychrome advertisement similar to that of FIG. 7A, respectively, under natural lighting (9A), as noted by means of the laser fluorescence technique of prior art (9B) and as it appears (9C and 9D) after two distinct digital processing similar to that which resulted in FIGS. 7C and 7D.

In accordance with the invention, and as partly shown by the Figure 1 of the accompanying drawings, the fingerprinting process digital essentially, whatever the hardware medium 2 bearing the imprint 1, to be applied on the imprint 1 to take a revealing powder with phosphorescent properties, to be submitted footprint 1 with adequate lighting, then create an area at least at the level of the support portion 2 carrying impression 1, to take one or more shots of fingerprint 1 in the dark and, finally, to view, archive, process, edit, transmit and / or analyze the resulting images said shots.

According to a first characteristic of the invention, the method aforementioned may advantageously consist of taking the shots at by means of a very sensitive digital camera 3, preferably of the charge transfer device type (coupled charge device CCD), and to transfer the acquired images to a digital processing 4 provided with storage means 5 and connected visualization 6, editing, printing 7 and / or 8 interface with switched or wireless networks of telecommunications, for the transmission of digital images acquired by means of said digital camera 3.

In order to increase the sharpness and the contrast in relation to the background consisting of the support 2, of the imprint 1 to be taken up, it is essential to use a powder or pigment fine-grained phosphorescent, the maximum emission of which, after excitation by white or natural light, is located in a wavelength range corresponding to the sensitivity range maximum of CCD 3 camera implemented, final images being obtained by summation of a variable number of shots of the phosphorescent imprint in the dark.

The aforementioned phosphorescent powder may consist of example, in a fine-grained phosphorescent pigment of the type known under the reference M1070 by the company MAIER GmbH & Co. KG (Germany).

The application of this pigment on the imprint 1 to be taken may be carried out according to conventional methods known to those skilled in the art trade, namely dusting of the imprint 1, then elimination of excess revealing phosphorescent pigment.

The support portion 2 carrying the imprint 1 covered with revealing pigment is preferentially submitted, with a view to its excitement, to white light lighting, provided by a lamp halogen 9, for example, but can also be exposed to ambient light.

A shot at the aforementioned exhibition, consecutive to the footprint 1 in the dark allows, due to the phosphorescence excited powder or developer pigment, to bring out and to isolate the footprint 1 from its support 2. The image of the fingerprint 1 taken is then completely independent of characteristics and properties (nature, color, roughness, texture, reflectivity, brightness, etc.) of the support portion 1 which carries it, these last ones not influencing the sharpness of the final image of imprint 1 which has excellent contrast.

In addition, obtaining a digital image by means of a CCD 3 camera with high resolution and very sensitive and by accumulation a plurality of identical shots (several hundred), dramatically increases the sharpness and contrast of the footprint 1 in relation to the support (compare in particular the Figures 2A, 3A, 4A, 5A, 6A and 7A in Figures 2B, 3B, 4B, 5B, 6B and 7B respectively).

In addition, the extremely short acquisition time of said successive shots (a few seconds), allows you to take advantage of the period of maximum emissivity of said phosphorescent pigment revealing, located immediately after establishment of darkness.

Unlike photographic processes, the CCD 3 camera allows, due to the absence of development, immediate visualization of the acquired image, with a view in particular of its control before archiving, exploitation or transmission and, it can then be planned to carry out, if necessary, either the acquisition of a new image of the imprint 1 obtained with parameters, such as the total number of shots to be summed, sharpness, contrast, distance, exposure time per shot or even duration and intensity of arousal, modified, i.e. treatment of the acquired image, or at least a portion of it last, in order to increase its quality and the sharpness of the pattern of the imprint and its distinctive characteristics. It's important to note that these treatments are carried out on a fingerprint statement, in the absence of the image of the support 2.

Figures 1 to 7 designated by C and D represent the images footprints of the corresponding figures designated by B, after binarization along the X axis (Figures C) and after binarization following the Y axis (Figures D), these two treatments improving areas distinct and complementary to the pattern of the imprint taken.

According to another characteristic of the invention, the method also consists of taking a photograph of the imprint 1 under normal lighting, the resulting image of which will be associated with the image of imprint 1 obtained in the dark, different texts or signs informative phosphors that can also be added to the when the digital images recorded before coding, archiving, editing, printing and / or transmission.

Thus the images of FIGS. 2A to 9A serve as proof of the presence of imprint 1 on given support 2 and images of Figures 2B to 9B constitute the working documents for identification.

The method according to the invention can be carried out by means of a device described below and mainly constitutes, on the one hand, by a means 3 of digital shots, on the other hand, by a unit 4 for digital processing, for example of the microcomputer type, for the acquisition, analysis, transfer, archiving and / or processing of the images delivered by said shooting means 3 digital and, finally, by viewing 6, ordering, editing, printing 7 and / or transmission 8 associated with said digital processing unit 4 (Figure 1).

The way digital photography is preferably presented under the form of a charge-coupled type digital camera (CCD), provided with suitable optics 10 as well as a light 10 '.

The digital processing unit 4 will comprise the different cards and software needed to acquire digital images delivered by the CCD 3 camera, when archived in memories associated 5, with their display on a screen 6 with different color palettes and associated histograms, when edited on removable computer media, when printed on paper by printers 7 and their transfer by switched networks digital to an identification center using an interface 8 adapted.

In addition, specific image processing software digital or assistance with shooting can also be put implemented by unit 4 at the request of the user, allowing, by example, to avoid overexposure or underexposure due to spatial variations in the intensity of phosphorescence, the acquisition of said digital images being, moreover, practically independent of the exposure time (variable so keep on going).

In addition, in order to facilitate the implementation of the method described above and take the shots in the issue period maximum of the phosphorescent powder or pigment, it can be provided lighting devices 9 and darkening 11 of the at least portion of support 2 carrying the imprint 1 to be taken, can be operated by means of a single command 12 in synchronism with digital shooting means 3.

It should be noted that, although more particularly described in connection with a process using an outlet device digital type of views and image processing, the powder phosphorescent described above, constituting a developer universal fingerprint, can also be used, independently of said process, in the context of methods "to revealing powder "traditional (for example by sampling the impression by means of an adhesive film), as a developer unique for taking fingerprints 1 on any medium 2 material in natural light.

Thanks to the invention, it is therefore possible to carry out a process simple fingerprint reader 1, using only one unique revealer whatever the nature and characteristics of the support 2 and enabling usable readings to be made, good quality, on many supports that are difficult to use or not currently studied through methods known (polychrome surfaces, wood, metals and glossy surfaces, plastic film or object, junction area between two supports of different natures, etc.), without any treatment particular of imprint 1 or support 2, likely to deteriorate these.

The implementation of this unique developer, resulting in very high contrast fingerprint images compared to support 2 (compare Figures 6B and 7B to Figures 8B and 9B for example) with a simple and harmless excitement, in combination with a means 3 direct digital shots with resolution and high sensitivity, allows real time and in situ operation readings taken, with the possibility of instant optimization of multiple digital images and manipulation of images obtained.

Furthermore, the entire device is relatively compact and easily transportable.

Of course, the invention is not limited to the mode of embodiment described and shown in the accompanying drawings. Of modifications are still possible, particularly from the point of view of constitution of the various elements, or by substitution of equivalents without going beyond the protection of the invention.

Claims (7)

1. Method of taking fingerprints on any material substrate, characterised in that it involves applying a developer powder with phosphorescent properties onto the fingerprint (1) on any substrate (2), adequately illuminating the fingerprint, forming a darkened region at least over the portion of the substrate (2) which bears the fingerprint (1), taking one or more pictures of the darkened fingerprint (1) in order to obtain a digital image by accumulation of a plurality of identical shots and finally displaying, filing, processing, editing, transmitting and/or scanning the resultant images.
2. Method according to claim 1, characterised in that it involves taking pictures using a very sensitive digital camera (3), preferably of the charge-coupled (CCD) type and transferring the images acquired to a digital processing unit (4) provided with storage means (5) and connected to devices for displaying (6), editing, printing (7) and/or interfacing (8) with switched or radio-frequency telecommunications networks.
3. Method according to claim 2, characterised in that it involves using a phosphorescent powder or pigment having fine grains of which the maximum emission, after excitation by a white light, lies within a wavelength range corresponding to the maximum sensitivity range of the CCD camera (3) used, the final images being obtained by summation of a variable number of successive shots.
4. Method according to any one of claims 2 and 3, characterised in that it involves displaying, for the control thereof, the digital image acquired prior to filing, handling by scanning and/or transmission and effecting, if applicable, either the acquisition of a new image of the fingerprint (1) obtained with parameters such as the total number of shots to be added, definition, contrast, distance, setting time per shot or again duration and intensity of excitation modified, or alternatively digital processing of the acquired image or of at least a portion thereof in order to increase its quality and the definition of the pattern of the fingerprint (1) and of its distinctive characteristics.
5. Method according to any one of claims 1 to 4, characterised in that it involves also taking pictures of the fingerprint (1) under normal illumination, the resultant image of which is associated with the image of the fingerprint (1) obtained in darkness, wherein various informative texts or signs can also be added at the moment of taking pictures of the digital images recorded prior to coding, filing, editing, printing and/or transmission.
6. Method according to any one of claims 1 to 5, characterised in that the various operations are carried out using a device consisting, on the one hand, of a digital picture-taking means (3) in the form of a digital camera of the charge-coupled (CCD) type provided with an adapted lens (10) and with a light intensifier (10'), on the other hand of a digital processing unit (4) of the microcomputer type for the acquisition, scanning, transfer, filing and/or processing of the images delivered by said digital picture-taking means (3) and, finally, of display (6), control, editing, printing (7) and/or transmitting (8) devices associated with said digital processing unit (4), said device also comprising illuminating devices (9) and darkening devices (11) at least for the portion of the substrate (2) bearing the fingerprint (1) to be recorded, which can be actuated using a single control means (12) synchronised with the digital picture-taking means (3).
7. Use of a powder having phosphorescent properties as a single developer for taking fingerprints (1) on any material substrate (2) in natural light by taking successive pictures of the phosphorescent fingerprint in darkness.

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